May 28, 2018 0600 UTC Day 1 Convective Outlook
Updated: Mon May 28 06:00:21 UTC 2018 (20180528 1200Z Day 1 shapefile | 20180528 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180528 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 57,968 837,029 Fort Collins, CO...Greeley, CO...Cheyenne, WY...Laramie, WY...Garden City, KS...
SLIGHT 129,371 1,728,445 Amarillo, TX...Thornton, CO...Boulder, CO...Longmont, CO...Rapid City, SD...
MARGINAL 391,707 20,883,620 Jacksonville, FL...Denver, CO...Minneapolis, MN...Aurora, CO...St. Paul, MN...
Probabilistic Tornado Graphic
20180528 1200 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 41,153 692,905 Fort Collins, CO...Greeley, CO...Cheyenne, WY...Laramie, WY...Garden City, KS...
2 % 144,674 10,676,086 Jacksonville, FL...Columbus, GA...Amarillo, TX...Tallahassee, FL...Savannah, GA...
Probabilistic Damaging Wind Graphic
20180528 1200 UTC Day 1 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 187,021 2,565,342 Amarillo, TX...Fort Collins, CO...Thornton, CO...Boulder, CO...Greeley, CO...
5 % 391,073 20,791,698 Jacksonville, FL...Denver, CO...Minneapolis, MN...Aurora, CO...St. Paul, MN...
Probabilistic Large Hail Graphic
20180528 1200 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 44,643 729,776 Fort Collins, CO...Greeley, CO...Cheyenne, WY...Laramie, WY...Garden City, KS...
30 % 57,774 803,181 Fort Collins, CO...Greeley, CO...Cheyenne, WY...Laramie, WY...Garden City, KS...
15 % 129,813 1,723,037 Amarillo, TX...Thornton, CO...Boulder, CO...Longmont, CO...Rapid City, SD...
5 % 305,445 11,488,729 Denver, CO...Minneapolis, MN...Aurora, CO...St. Paul, MN...Lubbock, TX...
   SPC AC 280600

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0100 AM CDT Mon May 28 2018

   Valid 281200Z - 291200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER A PORTION
   OF THE CENTRAL AND SOUTHERN HIGH PLAINS...

   ...SUMMARY...
   Severe thunderstorms with isolated very large hail, wind damage and
   perhaps a tornado threat are expected across parts of the Great
   Plains.  A couple of brief tornadoes will also be possible in the
   Southeast in conjunction with Alberto.

   ...Central and southern High Plains region...

   Shortwave trough currently rounding base of a cutoff upper low
   circulation centered over the Great Basin will continue northeast
   through eastern CO today. A quasi-stationary front reinforced by
   convective outflow will persist from northern CO northeast through
   NE into MN at the start of the period. Dryline will sharpen across
   western KS and west TX. East winds north of the stationary front
   will support influx of richer low-level moisture (50s dewpoints)
   into the Front Range, and dewpoints in the low 60s are expected east
   of the dryline beneath a warm elevated mixed layer. A corridor of
   moderate to strong instability will likely evolve from northeast CO
   into western NE and south through the High Plains of KS into west
   TX. The combination of diabatic warming, upslope flow and forcing
   for ascent attending the approaching shortwave trough should result
   in the initiation of thunderstorms over the higher terrain of
   northern CO into southeast WY. Other storms will likely develop
   farther south across western KS into west TX in association with
   dryline mixing and convergence. Vertical wind profiles with long
   hodographs will support supercells capable of producing very large
   hail, though a few tornadoes will be possible initially in vicinity
   of the boundary across northeast CO into southeast WY. Farther
   south, storms may initially be high based across western KS into the
   TX Panhandle with primary threats being very large hail and damaging
   wind. However, a window for at least a couple of tornadoes will
   exist during the early evening as the low-level jet strengthens and
   augments 0-1 km hodographs and as storms move into better low-level
   moisture. With time, storms may tend to congeal into several
   lines/clusters with primary threat becoming damaging wind by mid
   evening. 

   ...Southeast States...

   Alberto continues to entrain dry air, suggesting some diabatic
   heating will likely occur within the outer bands as the center moves
   north and inland today. Low-level hodographs north and east of the
   center will support some risk for low-level mesocyclones and a
   tornado or two with storms developing within the outer convergence
   bands during the afternoon and early evening.

   ...Lower Michigan...

   Moderate instability is expected as the boundary layer warms
   supporting inverted-V thermodynamic profiles. Vertical wind profiles
   with 25-30 kt effective bulk shear will support multicell storm
   modes and the environment will support some risk for damaging wind
   and hail. Primary limiting factor is potential sparse storm
   coverage.

   ..Dial/Gleason/Wendt.. 05/28/2018

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